During explosive forming, a generally tubular work piece is plastically widened by the developing internal pressure. Before the forming process, the work piece is situated in a closed die and then forced against the die cavity by the internal pressure. The high internal pressure required for this forms by ignition of a gas mixture in the interior; at detonation velocities to 5000 m/s, the die must withstand forces equivalent to about 400 t. Tight closure of the forming die is therefore of special significance for explosive forming.
An explosive forming method is described in the subsequently published German Patent Application 10 2005 025 660 “Device and Method for Explosive Forming.” The described device is used, in particular, to form a seal between the closed die and the tube-like work piece by a conical plug. This plug forms the continuation of an ignition tube, which can be moved between a work position against the die and a rest position at a standoff from the die. For this purpose, the force and stroke of a hydraulic cylinder are transmitted by a control element. In the laterally opened control element operated by the hydraulic cylinder, an oblique groove is situated for the ignition tube and an axially running straight groove for an engagement element. The axially guided ignition tube is moved over the oblique groove by movement of the control element. The engagement element is not engaged by movement of the control element, since it is guided to move in the straight groove.